Warning fatigue could become a real issue.
As emergency managers we are not the only people poised to issue warnings--and, actively doing so. There are many commercial warning systems out there today, starting with the banking and credit card industries. I've noted that I'm getting more notifications of deposits and withdrawls, or large purchases made with my credit card.
This article, which is a commercial for a particular solution made some good points about the anticipated growth in what they call "the alarm industry," which in our vernacular is warnings. See The next frontier of risk mitigation and disaster management.
Because of some prominent warning failures, I expect there will be a burgeoning industry of lawyers willing to take on clients who have been "injured" by either a failure to warn, late warnings or those that go awry.
In the above link, they had a list of considerations that I liked--not tied to hardware/software, but functionality. You might consider these in constructing your warning system.
Structuring a solution around effective monitoring and alerting requires an organization to ask these questions:
Claire Rubin, senior researcher, shared the link above.